To treat a stenosis portion or an occlusion portion inside a living-body lumen such as a blood vessel, a vascular channel and the like, in order to observe living-body properties inside the lumen or observe the state after treatment, there is used a catheter for diagnosis, which obtains an image of a living-body lumen by utilizing an inspection wave such as ultrasound, light or the like. An example of such a catheter is disclosed in Japanese Unexamined Patent Publication No. 2004-97286.
This kind of catheter includes a catheter main body provided with a window portion through which an inspection wave passes, and a drive shaft which is provided with a detector for transmitting & receiving the inspection wave and concurrently, which is installed advanceably and retractably in the axial direction inside the catheter main body. Then, while moving back, that is, by pulling back the drive shaft toward the proximal side inside the catheter, the inspection wave is transmitted & received by the detector.
However, when an operation such as insertion into a blood vessel or the like is carried out erroneously in a state in which the drive shaft remains pulled back, a defect such as a kink or the like can occur at a portion not supported by the drive shaft. When kinking or the like occurs, replacement of the catheter becomes necessary.